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We use uniform $W^{2,p}$ estimates to obtain corrector results for periodic homogenization problems of the form $A(x/\varepsilon):D^2 u_{\varepsilon} = f$ subject to a homogeneous Dirichlet boundary condition. We propose and rigorously…

Numerical Analysis · Mathematics 2020-06-17 Yves Capdeboscq , Timo Sprekeler , Endre Süli

In this work, we develop a novel Galerkin-L1-POD scheme for the subdiffusion model with a Caputo fractional derivative of order $\alpha\in (0,1)$ in time, which is often used to describe anomalous diffusion processes in heterogeneous media.…

Numerical Analysis · Mathematics 2016-02-02 Bangti Jin , Zhi Zhou

We consider the initial boundary value problem for the inhomogeneous time-fractional diffusion equation with a homogeneous Dirichlet boundary condition and a nonsmooth right hand side data in a bounded convex polyhedral domain. We analyze…

Numerical Analysis · Mathematics 2013-07-04 Bangti Jin , Raytcho Lazarov , Joseph Pasciak , Zhi Zhou

It is expensive to compute residual diffusivity in chaotic in-compressible flows by solving advection-diffusion equation due to the formation of sharp internal layers in the advection dominated regime. Proper orthogonal decomposition (POD)…

Computational Physics · Physics 2019-10-02 Jiancheng Lyu , Jack Xin , Yifeng Yu

This paper reports on a computational study of the model error in the LANS-alpha and NS-alpha deconvolution models of homogeneous isotropic turbulence. The focus is on how well the model error may be characterized by a stochastic force.…

Dynamical Systems · Mathematics 2017-06-23 Eric Olson

The focus of this paper is on the concurrent reconstruction of both the diffusion and potential coefficients present in an elliptic/parabolic equation, utilizing two internal measurements of the solutions. A decoupled algorithm is…

Numerical Analysis · Mathematics 2023-08-08 Siyu Cen , Zhi Zhou

In this paper, we present a numerical homogenization scheme for indefinite, time-harmonic Maxwell's equations involving potentially rough (rapidly oscillating) coefficients. The method involves an $\mathbf{H}(\mathrm{curl})$-stable,…

Numerical Analysis · Mathematics 2017-12-01 Barbara Verfürth

This paper rediscovers a classical homogenization result for a prototypical linear elliptic boundary value problem with periodically oscillating diffusion coefficient. Unlike classical analytical approaches such as asymptotic analysis,…

Numerical Analysis · Mathematics 2018-11-16 Daniel Peterseim , Dora Varga , Barbara Verfürth

Finding the symmetric and orthogonal decomposition (SOD) of a tensor is a recurring problem in signal processing, machine learning and statistics. In this paper, we review, establish and compare the perturbation bounds for two natural types…

Numerical Analysis · Computer Science 2017-06-06 Cun Mu , Daniel Hsu , Donald Goldfarb

In this paper, we combine concepts of the generalized multiscale finite element method and mode decomposition methods to construct a robust local-global approach for model reduction of flows in high-contrast porous media. This is achieved…

Computational Physics · Physics 2013-01-25 Mehdi Ghommem , Michael Presho , Victor M. Calo , Yalchin Efendiev

We propose an efficient numerical strategy for simulating fluid flow through porous media with highly oscillatory characteristics. Specifically, we consider non-linear diffusion models. This scheme is based on the classical homogenization…

Numerical Analysis · Mathematics 2020-02-04 Manuela Bastidas , Carina Bringedal , Sorin Pop , Florin Radu

Score-based generative models are a popular class of generative modelling techniques relying on stochastic differential equations (SDE). From their inception, it was realized that it was also possible to perform generation using ordinary…

Machine Learning · Statistics 2024-02-13 Joe Benton , George Deligiannidis , Arnaud Doucet

Out-of-distribution (OOD) detection and lossless compression constitute two problems that can be solved by the training of probabilistic models on a first dataset with subsequent likelihood evaluation on a second dataset, where data…

Computer Vision and Pattern Recognition · Computer Science 2021-12-13 Mingtian Zhang , Andi Zhang , Steven McDonagh

In this article, basing upon probabilistic methods, we discuss periodic homogenization of a class of weakly coupled systems of linear elliptic and parabolic partial differential equations. Under the assumption that the systems have rapidly…

Probability · Mathematics 2023-12-07 Nikola Sandrić

The notion of periodic two-scale convergence and the method of periodic unfolding are prominent and useful tools in multiscale modeling and analysis of PDEs with rapidly oscillating periodic coefficients. In this paper we are interested in…

Analysis of PDEs · Mathematics 2021-05-28 Martin Heida , Stefan Neukamm , Mario Varga

In $L_2(\mathbb{R}^d;\mathbb{C}^n)$, we consider a selfadjoint matrix strongly elliptic second order differential operator $\mathcal{A}_\varepsilon$, $\varepsilon >0$. The coefficients of the operator $\mathcal{A}_\varepsilon$ are periodic…

Analysis of PDEs · Mathematics 2018-04-10 Yulia Meshkova

We present an analysis of multilevel Monte Carlo techniques for the forward problem of uncertainty quantification for the radiative transport equation, when the coefficients ({\em cross-sections}) are heterogenous random fields. To do this,…

Numerical Analysis · Mathematics 2020-01-15 Ivan G. Graham , Matthew J. Parkinson , Robert Scheichl

The paper deals with homogenization of divergence form second order parabolic operators whose coefficients are periodic in spatial variables and random stationary in time. Under proper mixing assumptions, we study the limit behaviour of the…

Probability · Mathematics 2014-07-14 Marina Kleptsyna , Andrey Piatnitski , Alexandre Popier

The article describes an experimental method that allows to estimate the inhomogeneous and homogeneous linewidths of the photoluminescence band of a point defect in an amorphous solid. We performed low temperature time-resolved luminescence…

Disordered Systems and Neural Networks · Physics 2008-05-30 Michele D Amico , Fabrizio Messina , Marco Cannas , Maurizio Leone , Roberto Boscaino

We present a numerical investigation of stochastic transport in ideal fluids. According to Holm (Proc Roy Soc, 2015) and Cotter et al. (2017), the principles of transformation theory and multi-time homogenisation, respectively, imply a…

Fluid Dynamics · Physics 2018-09-28 Colin J. Cotter , Dan Crisan , Darryl D. Holm , Wei Pan , Igor Shevchenko